Reverse Polish Notation

Reverse Polish Notation, or RPN. It is also known as Postfix Notation. It is a style of mathematical notation.

RPN was first designed in the early 1960s and used by many calculator manufacturers, notably, HP. HP calculators still operate with RPN today.

In the words of Wikipedia, "In Reverse Polish notation the operators follow their operands." Thus, in order to perform the operation 2+2=4, a user would type 2, enter, 2, + which will return the answer of 4.

RPN is useful because it eliminates the need for parentheses while entering information and can be much faster than standard algebraic (infix) notation.

In the theater world, the ETC Congo and Congo Jr. use RPN as their input notation. On a Congo, to raise channel 5 to 75, a user would type 5, channel, 75, @